Reads tachometer signal from an engine using PIO state machines with built-in hour meter written in MicroPython.
When first powered on, the display will show the current total hours (left-aligned). After a few seconds, the tachometer will start (right-aligned). When the RPM value is greater than a threshold (implying the engine is on), the engine-on time value (in seconds) saved in the hours.json file will increment by 1 every second.
rpm_dividershould be adjusted specifically to your engine. In my case, the frequency from the tach signal at idle was reading ~120Hz. This would equate to 7200RPM at idle -- way too high. My engine idles between 900-1000 according to the owners manual. Dividing the final RPM value by 8 then produces an RPM of 900 at idle.rpm_thresholdshould be set to the minimum value of the RPM to consider the engine on. I found when turning the engine off, the RPM would get stuck on reading a small RPM value. Any RPM value above this threshold will show on the display and increment the hour meter, else the RPM value will be 0 and will not increment the hour meter.
